Due to the increasing awareness of the potential for extensive damage to the environment from large spills of oil at sea, various mechanical devices have been proposed to separate oil film from the surfaces of bodies of water. Such mechanical devices could be adapted to separate any two immiscible liquids and for reasons other than environmental spills. Some of the devices disclosed in the patent literature are discussed in the following.
U.S. Pat. No. 3,742,662, issued to Ortiz, discloses an apparatus which locally confines an oil spill and collects it in a plastic bag. U.S. Pat. No. 3,788,079, issued to Kirk, describes covering an oil film with a sheet with a weighted periphery to drive the oil to the center. U.S. Pat. No. 3,800,951, issued to Moulon, and 4,038,182, issued to Jenkins, suggest recovering an oil film by swirling the surface of the water to create centrifugal forces which separate the oil from the water. U.S. Pat. No. 3,959,136, issued to Ayers and Hemphill, describes a mechanical skimmer with inclined baffles which is moved along or rotates at the surface of a body of water. U.S. Pat. No. 4,146,482, issued to Shyu, uses the force of waves to drive oil into a collecting panel and tube. U.S. Pat. No. 4,196,087, issued to Gordon, uses screws to draw oily film into a central separator tank. U.S. Pat. No. 4,356,086, issued to Oberg, pumps an oil film and water downward and allows the oil to rise up into a collecting chamber. U.S. Pat. No. 4,449,850, issued to Cessou, describes a device to cap an underwater source of leaking oil. U.S. Pat. No. 4,485,013, issued to Cockman, discusses the filtration of water through filtration cones while hydrocarbon phases cannot penetrate the filter orifices. U.S. Pat. No. 4,610,788, issued to Ward, relies on the proper flotation height of a downspout so that only soil is drawn into its entrance. U.S. Pat. No. 4,684,467, issued to Cloud, describes a clarification vessel where a pipe located at the top removes the lighter phase and a second pipe located at the bottom removes the heavier phase. Canadian patent 1,242,655, issued to Juurmaa and Kalaja, is an extension of the concept in U.S. Pat. No. 3,959,136. A special apparatus immerses ice chunks and thereby removes any oil stuck to their surfaces. U.S. Pat. No. 4,790,936, issued to Renfrow, discusses a floating balloon which acts as an oil clarification tank into which the oily water is pumped. The oil rises to the top. U.S. Pat. No. 4,816,146, issued to Schertler, describes a series of oil settling tanks stacked on top of one another with the oily water being pumped into the top tank and flowing downwards. U.S. Pat. No. 4,818,399, issued to Midkiff and Owensville, describes a floating storage vessel inside which oil is separated in a settling tank and then stored in more tanks within the vessel. Canadian patent 2,012,733, issued to Essop, describes a series of three tanks in which a lighter phase separates out of the first tank by gravity separation, the middle tank collects emulsions and the last tank simply holds and discharges the heavier phase (usually water). Canadian patent 2,021,968, issued to Ortega, describes the removal of an oil film through floating funnels which direct the incoming oil/water mixture to a series of three gravity separation tanks. Canadian patent 2,035,585, issued to Todorski, describes a gravity separation vessel consisting of interior baffles which divide the separator into gradually larger and larger spaces, thereby enhancing the gravitational separation of oil. Canadian patent 2,053,326, issued to Ball, describes a vessel which utilizes swirling flow and has numerous flow channels designed to allow gases and solids to separate from liquids by gravity. Canadian patent 2,066,742, issued to Stephan, describes a suction extractor which is said to be capable of sucking a lighter phase off the top of a heavier phase. U.S. Pat. No. 5,108,600, issued to Rees and Koblanski, describes a nozzle which can be used to suck an oil film from the top of water and to spray the oil jet to a receiving tank. U.S. Pat. No. 5,122,280, issued to Russell and Russell, discusses a continuous flow device which allows oil to build up inside a vertical tank and to be withdrawn intermittently by a pump. U.S. Pat. No. 5,133,882, issued to Stearns, describes a floating barge which incorporates six different techniques to separate oil including an underwater flotation system to retrieve entrained oil droplets. U.S. Pat. No. 5,173,185, issued to Stokes, describes a rotating drum which uses a vacuum and steel bristles to scrub oil off the top of water.
The current invention is significantly different from any of these previous devices. It combines two separation techniques into one oil-recovery system, as well as providing a unique method to pump large quantities of oily water into the separator.